How To Replace Engine Knock Sensor 2000-06 Chevy Tahoe

All right. We want to disconnect the battery. Disconnect the negative cable, using an 8-millimeter ratchet wrench or a wrench and then slide that out of the way. Take this engine cover off. There's one screw right there. Use an 8-millimeter socket. Just raise the cover up and slide it forward. Now we're going to take this snorkel off. Use an 8-millimeter socket or a straight blade screwdriver, loosen up this worm clamp. And then over here, near the airbox attached to the mass air flow sensor. And there's going to be a bracket right here that's attached. This one is actually broken. Just use a trim tool to loosen that up. Then you can grab the snorkel, just rock it back and forth and take that off. I'm going to take this plate off. I'm going to use a 10-millimeter socket. Take these two bolts out. And for this back one, I'm just going to use a ratchet wrench because you can't get underneath here. If you had a shorter socket, you could. I'm going to take that bolt out and then just grab the plate. Take this nut off. There's a bracket right here that is holding this wiring harness on.

Just use a 10-millimeter socket to slide that out. Now we're going to disconnect the electrical connectors. You can disconnect the one right here on the purge valve. Just slide this lever up. And then on the alternator, push this little lever down. We're just trying to get slack so that we can move this out of the way. Disconnect this connector right here. This goes to a sensor down below there. Slide that out of the way. And then there's the injector sensor connectors. There's a little lock on here. You slide the injector lock up a little bit and then you can push down on the lock tab and pull it out. Sometimes you just pull this lock completely off. So this is how this works. Normally this is in here. So normally this lock is right here. You can just slide this up a little bit and then you can push on the tab and that should release. But sometimes if it's too difficult, just slide this lock completely out and it's a lot easier. So do that for the other injectors.

Three more on this side and then the other side. So disconnect the throttle body. Just slide this tab out, push down on the connector, slide it off. And then again with the fuel rail connectors for the injectors, take these off and disconnect the map sensor. Slide that connector out, disconnect it, and it should be all the connectors. And then you can just slide this harness out of the way, just go to the side. Now I'm just going to remove this connector, just slide that off and just set that aside. Now there's coolant hoses that go through the throttle body. So you have to take those coolant hoses off. You don't necessarily have to take the throttle body off, but you definitely have to take those hoses off. Make sure that the vehicle is cool when you go to take these hoses off. I'm going to use a couple of clamps on the hoses to prevent losing coolant. So then less coolant you have to top off. These just crushed the hose and you can take them off. The same on this hose right here.

You may use some hose clamp pliers, just slide these hose clamps down, and then you can try twisting. Twist the hose and slide it off and do the same for the other one. And I'll just use some hose removing pliers and slide those off. So this hose goes to the valve cover. Just take this hose off here, slide it off. Just like that. Set it aside. Now we want to disconnect the purge valve. Just push down on this lock right here, slide it up. Then this vacuum hose right here goes to this valve cover. Just slide it off the valve cover over here in the back. And you can either leave this connected to the intake or just try to slide it off over here like this. If it's out of your way, you can use a pick to loosen that up. Going to slide the pick around here. I'm just trying to twist this off a little bit. There we go, and slide that down. Slide that out of the way. Now there is some dirt and debris at the bottom of the intake. Before I disconnect the fuel line and have gasoline in that area, you could use a vacuum to try to vacuum that up or just use a blow gun and just blow it away.

Now there is going to be pressure in the fuel line. So you want to release that pressure before you pop the line off. And there's a little cap with a Schrader valve right there. Take the cap off. You can take a rag just so the fuel doesn't spray everywhere. And what you want to do is push on that Schrader valve and just release the pressure. Once you get in that area, cover this up and push the valve. You should wear safety glasses while you're doing this. There's no pressure in this. So that's good. The fuel line connects right here and there's this clip. You just slide it up and then slide it out. I'm going to have to use a screwdriver to bend that up. Slide that up, set that aside. And then you're going to need a special tool to take this off. Go around the fuel line. And you're going to press it into this, into the fuel line, and then slide the line off. There's little fingers in there.

There we go. I see the little fingers right there. And then you can take this tool off. Now this vehicle has a hydraulic booster. It doesn't have a vacuum booster. If you have a vehicle with the vacuum booster, you're going to need to take that hose off either at the booster on the back of the intake. Now use an 8-millimeter socket. And there's a bolt right here, right here, right here, and then two in the back. So five bolts per side. Take those bolts, loosen them up. They should be caged so they're not going to come out of the intake. You just got to loosen them. With all those bolts loose, you can grab the intake and then slide it up. And this hose you're going to have to feed it underneath the fuel line right here. You could take the fuel lines off if it makes it easier, but you don't have to.

To make it easier I'm just going to pop the line off right here. It's hard to grab that while the intake is still on there, but just push down on the lock and then slide it up. Just grab the intake and slide it out. All right, I'm going to use a trim tool and just pry up this little grommet right here. You can slide it up on the wire and then this one as well. If you're reusing these wires, just be careful. Although a lot of times the plastic connector breaks so it's a good idea to just replace these together. And then I'll just take the tool and just try to squeeze the connector. I'll just squeeze it like that and it spreads. All right, there you go. And there's the wiring harness. Now we're going to take a 22-millimeter socket and loosen up the sensor. Once it's loose, you should be able to do it by hand and then take the sensor out. You're gonna take the new knock sensor. Now these are pretty sensitive so you don't want to drop these. And then just make sure there's nothing in the valley right there. If there's anything in there, clean it out with either compressed air or a vacuum. Take the new sensor, gently screw it in.

So it's very important to torque these properly. You want to torque these to 15 foot-pounds. Then I'm going to do the same for the other one. Right, now you take this wiring harness. Now the green wire, at least on this harness is going to go to the back sensor. Just line that up, lock it in. And then the blue one's going to the front harness. Just match the wire up the way it goes. That's good. Now we can push the grommet into place and do the same for the back one. That looks good.

Now I'm just going to move this connector back here for when I put the intake on. Now I'm just cleaning up the surface area where the intake goes, where the intake gasket meets the head. You can use a small razor blade, just be careful. You don't want to gouge the metal. Just use it lightly, or a small scraper and just try not to get any of the dirt into the intake ports. And you can take a rag and a little brake parts cleaner and just clean up the surface. You want to replace these gaskets whenever you take the intake off. There's a little clip right here. Just slide that off, and a clip right here, and right here, and just clean up any of this area, try to get some of that carbon off. Try not to let it go into the intake itself. And just take a new gasket, line it up, lock it down and do the same with the other side. And right before we put the intake on, just take a blowgun, just to make sure nothing got into the ports.

All right. Take the intake and just line it up. Just make sure none of the wires get in the way. That looks good. And take this EVAP line. Let me just line it up in the back, then I'll lock it down. That's good. You can lock it down right here as well. Just so we don't lose this connector, just grab this and just line it. Click this in position right here. We'll connect it later. That's good. Now we're going to torque these down. Now there's two torque sequences that you do. The first pass, you're going to torque these to 3.7 foot-pounds. And this is number one right here. Now 3.7 is pretty much just snug. So that's number one. Number two is right here, and number three. You go to the next one in the back. Not all the way to the back, just right there. And number four is right here. So from the middle, the next one forward. Number five is on the passenger side, the next one back. And number six right here on the driver's side.

Number seven, the most forward one on the driver's side. Number eight for this one back on the passenger side. Number nine for this one back on the driver's side. And number 10. All right. So on the second pass, we're going to torque these to 7.4 foot-pounds in the same routine, same procedure. So number one right here, number two right here, number three you go further back. Number four on the other side, and number five right here. Number 6, number 7, number 8 back here, number 9 right here, and last, number 10 right here. And now we'll install the fuel line. Just line that up, lock it in place. Then you take that lock, put that back on, snap it down. Now take this line that goes over to the valve cover and wind that up. And then put that right there and then take this hose, get that lined up. And then if you had the hose for the brake booster, you're going to want to hook that up. Now we can hook up these coolant lines under the throttle body. Line those up.

And move the clamps over. Same with the other one. Pretty much put those where they were when they came off and you can take the hose clamps off. Where the hose pinchers, take those off. And then from the back of the engine, start hooking up the wires. So the map sensor, my net wire up connector. Then connect this connector right here. And then all the fuel injector connectors, line those up. Lock those down and then put the lock on as well. Let's see. And then push that down. You're going to wiggle them a little bit, make sure they're on there properly. And just take this bracket, just line that up. That's good. Connect the alternator and the purge valve. And then connect the injectors on the passenger side, same as the driver's side. Just line them up, lock them in place, push down on the lock. And connect the throttle body, line that connector up, push down on the lock, take this nut, put that up on that bracket and snug that up. And take this bracket, line this up, and then put the bolts in.

And snug these up. Now, put the snorkel on, just line it up over the throttle body and then over the mass airflow sensor. And just tighten the worm clamp down. Just snug. That's good. Reattach that bracket. Just slide that through the pinhole right there. That's good. And take the engine cover and line it up. Get the bolt started, and snug it down. Now we can hook up the battery. Line it up and get it started and snug it up. Just make sure it's not loose. That's good.